1. Field of the Invention
The present invention relates to a fuel injection valve used for an internal combustion engine and in particular to a fuel injection valve that has a plurality of fuel injection holes and can improve atomizing performance by jetting swirl fuel from the fuel injection holes.
2. Description of the Related Art
The fuel injection valve disclosed in JP-2004-278464-A is known as a conventional technology for promoting the atomization of fuel jetted from the fuel injection holes by the use of swirl flow.
The fuel injection valve includes a valve seat member having a valve seat which cooperates with a valve body and has an opening at its downstream end toward the front end face of the valve seat member, and includes an injector plate joined to the front end face of the valve seat member. There are provided lateral-directional passages communicating with the downstream end of the valve seat and swirl chambers each formed by tangentially opening the corresponding downstream ends of the lateral-directional passages, between the valve seat member and the injector plate. The injector plate is bored with fuel injection holes each adapted to jet the fuel subjected to swirl in the swirl chamber. The curvature radius of the inner circumferential surface of the swirl chamber is gradually reduced from the upstream side toward the downstream side in the direction along the inner circumferential surface of the swirl chamber. In other words, the curvature is gradually increased from the upstream side toward the downstream side in the direction along the inner circumferential surface of the swirl chamber. In addition, the inner circumferential surface of the swirl chamber is formed along an involute curve having a base circle in the swirl chamber.
In this fuel injection valve, an overlapping surface between the thick-walled portion of a passage plate and the injector plate is formed to have two slope faces inclined in a V-shape with respect to the axis of the valve seat. In addition, the fuel injection holes are divided into two sets each arranged at a slant in directions opposite to the other.
With the configuration described above, the atomization of fuel from each of the fuel injection holes can effectively be promoted. In addition, the injecting direction of fuel can be varied.
The fuel injection valve described in JP-7-35001-A is known as a conventional technology for promoting the atomization of fuel by the use of swirl force and for distributing fuel into a plurality of holes to make mixing with air satisfactory.